Re: why doesn't the range on this interval match the plot range?

• To: mathgroup at smc.vnet.net
• Subject: [mg66432] Re: [mg66394] why doesn't the range on this interval match the plot range?
• From: Bob Hanlon <hanlonr at cox.net>
• Date: Fri, 12 May 2006 02:03:19 -0400 (EDT)
• Reply-to: hanlonr at cox.net
• Sender: owner-wri-mathgroup at wolfram.com

```Parabola[x_]=4x^2+53x+160;
BeginPoint=-8;
EndPoint=-5;
Plot[Parabola[x],{x,BeginPoint,EndPoint}];

Carry out the interval operations step-by-step to see why it should not be the range.

xi=Interval[{BeginPoint,EndPoint}];

4xi^2

Interval[{100,256}]

53xi

Interval[{-424,-265}]

%+%%+160

Interval[{-164,151}]

The range is

Off[Maximize::wksol];
#[{Parabola[x],BeginPoint<x<EndPoint},
x][[1]]&/@{Minimize,Maximize}

{-(249/16), -5}

Bob Hanlon

---- Chris Chiasson <chris at chiasson.name> wrote:
> Parabola[x_]=4x^2+53x+160
> BeginPoint=-8;
> EndPoint=-5;
> Plot[Parabola[x],{x,BeginPoint,EndPoint}]
> Parabola[Interval[{BeginPoint,EndPoint}]]
>
> --
> http://chris.chiasson.name/
>

```

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